Luis Amell / MLX90614

Added the functions to read and set the emissivity of the sensor.

mlx90614.cpp@6:689f0dab386c, 2020-05-11 (annotated)

Committer:
lamell
Date:
Mon May 11 18:38:27 2020 -0400
Revision:
6:689f0dab386c
Parent:
5:3c4431224932
Child:
7:be827071bcb0
Added the commands to Set and Read the Emissivity of the sensor. It's based on a brute force approach in the meantime,

until I figure out the mysterious polynomial crc.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
aquahika 1:4a60d3f1e91e 1
aquahika 1:4a60d3f1e91e 2 #include "mlx90614.h"
aquahika 1:4a60d3f1e91e 3
aquahika 1:4a60d3f1e91e 4 MLX90614::MLX90614(I2C* i2c,int addr){
aquahika 1:4a60d3f1e91e 5
aquahika 1:4a60d3f1e91e 6 this->i2caddress = addr;
aquahika 1:4a60d3f1e91e 7 this->i2c = i2c;
aquahika 1:4a60d3f1e91e 8
aquahika 1:4a60d3f1e91e 9 }
aquahika 1:4a60d3f1e91e 10
aquahika 1:4a60d3f1e91e 11
aquahika 1:4a60d3f1e91e 12 bool MLX90614::getTemp(float* temp_val){
aquahika 1:4a60d3f1e91e 13
aquahika 1:4a60d3f1e91e 14 char p1,p2,p3;
aquahika 1:4a60d3f1e91e 15 float temp_thermo;
aquahika 1:4a60d3f1e91e 16 bool ch;
aquahika 1:4a60d3f1e91e 17
aquahika 1:4a60d3f1e91e 18 i2c->stop(); //stop i2c if not ack
lamell 6:689f0dab386c 19 thread_sleep_for(10);
aquahika 1:4a60d3f1e91e 20 i2c->start(); //start I2C
aquahika 1:4a60d3f1e91e 21 ch=i2c->write(i2caddress); //device address with write condition
aquahika 1:4a60d3f1e91e 22
aquahika 1:4a60d3f1e91e 23 if(!ch)return false; //No Ack, return False
aquahika 1:4a60d3f1e91e 24
aquahika 1:4a60d3f1e91e 25 ch=i2c->write(0x07); //device ram address where Tobj value is present
aquahika 1:4a60d3f1e91e 26
aquahika 1:4a60d3f1e91e 27 if(!ch)return false; //No Ack, return False
aquahika 1:4a60d3f1e91e 28
aquahika 1:4a60d3f1e91e 29
aquahika 1:4a60d3f1e91e 30 i2c->start(); //repeat start
aquahika 1:4a60d3f1e91e 31 ch=i2c->write(i2caddress|0x01); //device address with read condition
aquahika 1:4a60d3f1e91e 32 if(!ch)return false; //No Ack, return False
aquahika 1:4a60d3f1e91e 33
aquahika 1:4a60d3f1e91e 34 p1=i2c->read(1); //Tobj low byte
aquahika 1:4a60d3f1e91e 35 p2=i2c->read(1); //Tobj heigh byte
aquahika 1:4a60d3f1e91e 36 p3=i2c->read(0); //PEC
aquahika 1:4a60d3f1e91e 37
aquahika 1:4a60d3f1e91e 38 i2c->stop(); //stop condition
aquahika 1:4a60d3f1e91e 39
aquahika 1:4a60d3f1e91e 40
aquahika 1:4a60d3f1e91e 41 temp_thermo=((((p2&0x007f)<<8)+p1)*0.02)-0.01; //degree centigrate conversion
aquahika 1:4a60d3f1e91e 42 *temp_val=temp_thermo-273; //Convert kelvin to degree Celsius
aquahika 1:4a60d3f1e91e 43
aquahika 1:4a60d3f1e91e 44 return true; //load data successfully, return true
lamell 5:3c4431224932 45 }
lamell 5:3c4431224932 46
lamell 5:3c4431224932 47 float MLX90614::GetEmissivity(void) {
lamell 5:3c4431224932 48 char p1,p2,p3;
lamell 5:3c4431224932 49 float temp_thermo;
lamell 5:3c4431224932 50 bool ch;
lamell 5:3c4431224932 51
lamell 6:689f0dab386c 52
lamell 6:689f0dab386c 53 i2c->stop(); //stop i2c if not ack
lamell 6:689f0dab386c 54 thread_sleep_for(10);
lamell 6:689f0dab386c 55 i2c->start(); //start I2C
lamell 6:689f0dab386c 56 ch = i2c->write(i2caddress); //device address with write condition
lamell 5:3c4431224932 57
lamell 5:3c4431224932 58 if(!ch)return -90.0f; //No Ack, return False
lamell 5:3c4431224932 59
lamell 6:689f0dab386c 60 ch = i2c->write(0x24); //device ram address where Tobj value is present
lamell 5:3c4431224932 61
lamell 5:3c4431224932 62 if(!ch)return -91.0f; //No Ack, return False
lamell 5:3c4431224932 63
lamell 5:3c4431224932 64
lamell 6:689f0dab386c 65 i2c->start(); //repeat start
lamell 6:689f0dab386c 66 ch = i2c->write(i2caddress | 0x01); //device address with read condition
lamell 5:3c4431224932 67 if(!ch)return -92.0f; //No Ack, return False
lamell 5:3c4431224932 68
lamell 6:689f0dab386c 69 p1 = i2c->read(1); //Tobj low byte
lamell 6:689f0dab386c 70 p2 = i2c->read(1); //Tobj heigh byte
lamell 6:689f0dab386c 71 p3 = i2c->read(0); //PEC
lamell 5:3c4431224932 72
lamell 6:689f0dab386c 73 i2c->stop(); //stop condition
lamell 6:689f0dab386c 74
lamell 6:689f0dab386c 75 debug_if(debug_mlx90614==true,"p2: %02X, p1: %02X\r\n",p2,p1);
lamell 5:3c4431224932 76
lamell 5:3c4431224932 77 return (((p2<<8) + p1)/65535.0f); //load data successfully, return true
lamell 5:3c4431224932 78 }
lamell 5:3c4431224932 79
lamell 5:3c4431224932 80 int MLX90614::BlankEEPROM(int em) {
lamell 5:3c4431224932 81 uint8_t p1[5];
lamell 5:3c4431224932 82 float temp_thermo;
lamell 5:3c4431224932 83 bool ch;
lamell 5:3c4431224932 84
lamell 6:689f0dab386c 85 p1[0]=i2caddress;
lamell 5:3c4431224932 86 p1[1]=0x24;
lamell 5:3c4431224932 87 p1[2]=0x00;
lamell 5:3c4431224932 88 p1[3]=0x00;
lamell 5:3c4431224932 89
lamell 6:689f0dab386c 90 i2c->stop(); //stop i2c if not ack
lamell 6:689f0dab386c 91 thread_sleep_for(10);
lamell 6:689f0dab386c 92 i2c->start(); //start I2C
lamell 6:689f0dab386c 93 ch = i2c->write(p1[0]); //device address with write condition
lamell 5:3c4431224932 94 if(!ch)return -1; //No Ack, return False
lamell 5:3c4431224932 95
lamell 6:689f0dab386c 96 ch = i2c->write(p1[1]); //device ram address where Tobj value is present
lamell 5:3c4431224932 97 if(!ch)return -2; //No Ack, return False
lamell 5:3c4431224932 98
lamell 6:689f0dab386c 99 ch = i2c->write(p1[3]); //Tobj low byte
lamell 5:3c4431224932 100 if (!ch) return -3;
lamell 5:3c4431224932 101
lamell 6:689f0dab386c 102 ch = i2c->write(p1[2]); //Tobj heigh byte
lamell 5:3c4431224932 103 if (!ch) return -4;
lamell 5:3c4431224932 104
lamell 5:3c4431224932 105
lamell 5:3c4431224932 106
lamell 6:689f0dab386c 107 ch = i2c->write(em);
lamell 5:3c4431224932 108 if (!ch) return -5;
lamell 5:3c4431224932 109
lamell 6:689f0dab386c 110 i2c->stop(); //stop condition
lamell 5:3c4431224932 111
lamell 6:689f0dab386c 112 debug_if(debug_mlx90614==true,"Em: %1.3f\r\n",GetEmissivity());
lamell 5:3c4431224932 113
lamell 5:3c4431224932 114 return 0;
lamell 5:3c4431224932 115 }
lamell 5:3c4431224932 116
lamell 6:689f0dab386c 117 int MLX90614::InternalSet(uint8_t *p, int idx) {
lamell 6:689f0dab386c 118 uint8_t ch;
lamell 6:689f0dab386c 119
lamell 6:689f0dab386c 120 i2c->stop(); //stop i2c if not ack
lamell 6:689f0dab386c 121 thread_sleep_for(10);
lamell 6:689f0dab386c 122 i2c->start(); //start I2C
lamell 6:689f0dab386c 123 ch = i2c->write(p[0]); //device address with write condition
lamell 6:689f0dab386c 124 if(!ch)return -1; //No Ack, return False
lamell 6:689f0dab386c 125
lamell 6:689f0dab386c 126 ch = i2c->write(p[1]); //device ram address where Tobj value is present
lamell 6:689f0dab386c 127 if(!ch)return -2; //No Ack, return False
lamell 6:689f0dab386c 128
lamell 6:689f0dab386c 129 ch = i2c->write(p[2]); //Tobj low byte
lamell 6:689f0dab386c 130 if (!ch) return -3;
lamell 6:689f0dab386c 131
lamell 6:689f0dab386c 132 ch = i2c->write(p[3]); //Tobj heigh byte
lamell 6:689f0dab386c 133 if (!ch) return -4;
lamell 6:689f0dab386c 134
lamell 6:689f0dab386c 135 ch = i2c->write(idx);
lamell 6:689f0dab386c 136 if (!ch) return -5;
lamell 6:689f0dab386c 137
lamell 6:689f0dab386c 138 i2c->stop(); //stop condition
lamell 6:689f0dab386c 139
lamell 6:689f0dab386c 140 return 0;
lamell 6:689f0dab386c 141 }
lamell 6:689f0dab386c 142
lamell 6:689f0dab386c 143 int MLX90614::SetEmissivity(float *em) {
lamell 5:3c4431224932 144 uint8_t p1[5];
lamell 6:689f0dab386c 145 //float temp_thermo;
lamell 5:3c4431224932 146 bool ch;
lamell 6:689f0dab386c 147 int result;
lamell 5:3c4431224932 148 uint8_t num[2];
lamell 5:3c4431224932 149
lamell 6:689f0dab386c 150 uint16_t res;
lamell 6:689f0dab386c 151
lamell 6:689f0dab386c 152 *em = 65535.0f * (*em);
lamell 5:3c4431224932 153
lamell 6:689f0dab386c 154 num[0] = (int)(*em) & 0xff;
lamell 6:689f0dab386c 155 num[1] = (int)(*em) >> 8;
lamell 5:3c4431224932 156
lamell 6:689f0dab386c 157 p1[0]=i2caddress;
lamell 5:3c4431224932 158 p1[1]=0x24;
lamell 5:3c4431224932 159 p1[2]=num[0];
lamell 5:3c4431224932 160 p1[3]=num[1];
lamell 5:3c4431224932 161
lamell 6:689f0dab386c 162 for (res=0;res<0xff;res++) {
lamell 6:689f0dab386c 163 result = BlankEEPROM(res);
lamell 6:689f0dab386c 164 if (result != -5) break;
lamell 6:689f0dab386c 165 }
lamell 6:689f0dab386c 166 debug_if(debug_mlx90614==true,"Blank EEPROM: %d, ",result);
lamell 5:3c4431224932 167
lamell 6:689f0dab386c 168 for (res=0;res<0xff;res++) {
lamell 6:689f0dab386c 169
lamell 6:689f0dab386c 170 result = InternalSet(p1, res);
lamell 5:3c4431224932 171
lamell 6:689f0dab386c 172 if ((res > 0xff) || (result == 0) ){
lamell 6:689f0dab386c 173 break;
lamell 6:689f0dab386c 174 }
lamell 6:689f0dab386c 175 }
lamell 5:3c4431224932 176
lamell 6:689f0dab386c 177 debug_if(debug_mlx90614==true,"Emissivity Set to: %1.3f\r\n",GetEmissivity());
lamell 5:3c4431224932 178
lamell 5:3c4431224932 179 return 0;
lamell 5:3c4431224932 180 }